Warp letting-off in textile looms



March 29, 1955 BEER 2,705,024

WARP LETTING-OFF IN TEXTILE LOOMS Filed June 26, 1952 INVENTOR. Tv us BEE United States Patent WARP LETTING-OFF IN TEXTILE LOOMS Julius Beer, Wertheim am Main, Germany, assignor to Ph. Kurtz Eisenwerk, Hasloch (Main), Germany Application March 25, 1953, Serial No. 295,661

Claims priority, application Germany June 30, 1951 8 Claims. (Cl. 139-109) This invention concerns the automatic letting-off of the warp in textile looms.

It is important for the production of uniformly closely woven fabrics to maintain a constant tension of the warp threads on the loom. In order to obtain this it is generally attempted to compensate the influence of the diminishing leverage by means of which the warp threads engage on the warp beam which during weaving gradually reduces in diameter, by progressively releasing the warp beam brake in correspondence with the decrease of the diameter. This however, necessitates continuous super vision and adjustment of the brake by the operatives. Even the expensive and most complicated regulators which are responsive to the winding diameter of the warp beam and effect an automatic release of the brake do not operate in the case of sensitive cloth so satisfactory that an additional individual supervision by the operatives could be dispensed with with certainty. This also applies to those constructions in which the periodic change of the tension which arises in the warp itself during the shedding and the beating up of the weft is employed in order to adjust the back rest depending upon the constant decrease of diameter of the warp beam and at the same time gradually to release the warp beam brake correspondingly. slackening the brake gradually depending upon the diameter of the warp beam fails to work in the case of sensitive cloth for the simple reason that in practice a changing condition of the brake surfaces must be expected which can be so effective that the cloth is not uniformly close-woven.

The invention aims at avoiding the aforementioned disadvantages and obtaining a practically perfect and constant tension of the warp with simple means. Thus, the change in the tension of the warp is allowed to act on the warp beam brake through the movable whip bar in accordance with a slackening in such a manner that merely the periodic fluctuations of the warp tensionduring the beating up of the weft and/or the sheddingare utilized for the purpose of producing periodic whip bar movements against a restoring force, as well as to supply the force for the periodic slackening of the brake, which has been tightened by a separate closing force independent thereof. A particularly sensitive response of the release of the brake and consequently an extremely uniform tension of the warp is obtained, if the whip bar is disposed pivotally about a short lever arm and the brake arm of this lever is given a direction which lies substantially vertical to the direction taken by the warp from the whip bar to the shed, and WhlCh corresponds approximately with the direction of the warp coming from the warp beam. Therefore the warp should run parallel to the brake arm of the lever from the warp beam to the whip bar and leave same vertically thereto in direction of the shed, breast beam, sand roll from where the warp receives its tension. The short lever arm of the whip bar together with a second long lever preferably forms a double-armed lever which in turn engages on the long arm of a second doublearmed lever, whose other, particularly short arm, is capable of overcoming the closing force of the brake. In the meantime, the spring which engages on the long arm independent upon the closing force of the brake, is so dimensioned and pre-tensioned that it can maintain the balance of the normal warp tension, but gives way with each increase of the warp tension. Small changes The known method of Patented Mar. 29, 1955 in the tension of individual threads necessitate in the usual manner a normal rocking operation on the back rest provided for this without the latter being in the position to overcome the force of the spring engaging on the long lever arm. Each greater increase of the warp tension during the beating up of the weft and/or the shedding causes however a deflection of the second double-armed lever which reduces the closing force of the brake for the duration of the impulse and renders possible a slackening of a piece of the warp from the warp beam which up to then had been held firmly nonrotatably by the brake.

The invention will be described further by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a diagrammatic side elevation of a loom;

Figs. 2 and 3 are diagrammatic side elevations, partly in section, showing two embodiments for the fitting of a warp brake in the loom according to Fig. 1; and

Fig. 4 is a part elevation of the loom in direction of the arrow I in Fig. l.

Numeral 1 designates the loom frame in which the warp beam 2, whip bar 3, breast beam 4, sand roll 5 and cloth beam 6 are mounted. The warp 7 runs from the warp beam 2 over the whip bar 3, lease rods 8, through the heddles 9 over the breast beam 4 and the sand roll 5 on to the cloth beam 6.

The whip bar 3 is pivotally mounted about an axis 15. The whip bar 3 and the lever 16 pivot together about the axis 15, the lever 16 forms a longer lever arm of a bell crank lever, whose shorter arm is the distance between the pivot point and the warp supporting surface portion on which the tension of the warps acts. The short arm is disposed approximately perpendicular relative to the running-off direction of the warp and/or to the direction of the tension pof the warp and has approximately the direction of the warp threads running on to the whip bar 3 from the warp beam 2. The long lever arm is connected to a rod 17. The rod 17 is coupled with a brake release lever 11 which is shown incomplete in Fig. l and in Figs. 2 and 3 is shown in two different embodiments of a warp beam brake, on an enlarged scale and complete. One end of a tension spring 12 engages on the brake release: lever 11 which is rotatably mounted on a pin 10 of the machine framing 1. This spring may be so arranged with its other end on the frame 1 according to Figs. 1 and 3 and/ or according to Fig. 2, on a lug 20 that its pre-rtensioning is adjustable by means of a hand wheel 21. The warp beam brake includes two brake shoes 18; 19. The lower brake shoe 18 is secured to the machine frame 1 in the manner of a bracket and constructed in form of a support bearing-well of the warp beam. A bearing 22 supports a set screw 23 which prevents undesired swinging movements of the brake lever 11. The upper brake shoe 19 is pivotally mounted about a pin 24 of the lower brake shoe 18. A tension bolt 27 passes through lugs 25 and 26 respectively of the brake shoes 18, 19, and a nut 28 is screwed onto the upper end of this bolt 27 to act as rigid but detachable stop. A collar :29 between the two projections 25, 26 prevents the tension bolt 27 being pulled in a downward direction out of the lug 25. A compression spring 31 is incorporated between the projection 25 and an adjustment nut 30 of the tension bolt 27. By means of this adjustment nut 30 the pressure of the pressure spring 31 is regulated in such a manner that it pulls the two brake shoes 18, 19 against the brake drum 14 of the warp beam with such a force that the warp beam is prevented from rotating. Another set screw 32 is fixed adjustably opposite the bottom end of the bolt 27 on a very short arm 33 of the brake release lever 11 to the right of the point of rotation 10.

As the warp beam 2 is held non-rotatably under the pressure of the spring 31 by the brake shoes 18, 19 it can only be rotated for the purpose of letting off the warp if the warp beam brake 14, 18, 139, 31 is at least partially unloaded.

The warp tension p acts on the whip bar 3 in such a manner that the latter together with the lever 16 tends to swing in the direction of the arrow 34.. This swinging movement counteracts the spring 12 engaging on the lever 16 over the lever 11 and the guide rod 17. The spring 12 is adjusted to a definite nominal value depending upon the actual cloth material to be woven by turning a hand wheel, and in fact in such a manner that the spring 12 compensates the normal tension 2 of the warp with which the material in question is to be woven. With a lesser tension p of the warp the lever 11 lies against the stop 23 and allows the warp threads to execute the usual rocking operation on the practically stationary whip bar 3.

If the tension p of the warp during the beating up of the weft through the loom slay and/or already on opening of the shed exceeds the normal tension, for example, by 1% the whip bar rotates and therewith the lever 16 swings about the axis in the direction of the arrow 34; and the set screw 32 disposed in the short arm 33 of the lever 11, by moving away from the tension bolt 27 cases the warp beam brake 14, 18, 19, 31 by compressing the spring 31. In this unloaded condition of the brake the tension p of the warp is strong enough to turn the warp beam 2 for the purpose of letting off a length of the Warp. As this results in an immediate reduction of the warp tension, the whip bar 3 immediately swings back to the right and the lever 11 coupled thereto cannot then combine to ease the brake. The spring 31 thus becomes fully effective again and the warp beam 2 is held non-rotatably again immediately after letting off a piece of warp which reinstates the normal warp tension, until the performance is repeated shortly afterwards, as soon as and as often as the beating up of the weft and/or the shedding again creates warp tension p exceeding the normal tension. The whip bar 3 and the rods 16, 17, 11 are thus practically always in motion for the continuous slackening and tightening of the brake. This constant alternate unloading and tightening again of the warp brake for the purpose of letting off and/ or stopping of the warp in dependence upon, and solely actuated by slight variations of the tension of the warp, as they occur during the cloth stop and the shedding, is an essential feature of the invention. It is further essential that after each letting off of the warp only the strongly pre-tensioned spring 31 still acts on warp beam brake and tightens same to such an extent that the tension p of the warp is unable to rotate the warp beam any further. The adjustment is preferably so effected that the short end 33 of the double-armed lever 11 does not come into contact with the screw, but is in equilibrium with the warp tension p as long as the tension is unable to move the whip bar 3 to the left. It is also important that the spring 12 and warp tension acting on the whip bar 3 in an adjusting manner, engage on an arm of the lever 11, which arm is very long in relation to the arm 33. This renders possible the very delicate adjustment of the device by the screw 21 to that warp tension p which corresponds to the actual cloth being worked-up on the loom,

and with the smallest variations of the warp tension 2 even the reliable and easy unloading of the strongly pretensioned spring 31 of the warp beam every time the warp has to be let off.

After unscrewing the upper stop nut 28 the upper brake shoe 19 may be swung upwards to such an extent about its pivot pin 24 that the warp beam 2 can be lifted out of its bearings. The collar 29 thus prevents the screw 27 from falling out and the brake spring 31 from becoming completely detached. After inserting a warp beam in the lower brake shoe 18, which acts as rotary bearing, the upper brake shoe 19 may be swung back into position and the nut 28 screwed on again. The loom is now ready for operation as the braking effect on the warp beam determined merely by the tension of the brake spring 31, has not been changed by the above-mentioned operations.

The embodiments shown in Figure 3 difiers from the exampleaecording to Fig. 2 by the fact that a brake band 35 is used as braking means. The brake release lever 11 is mounted on a supporting bracket 36 secured to the machine frame 1. One end 38 of the brake band is anchored by means of an adjustable tension bolt 39 at the head 37 of the bracket 36. The movable end 40 of the brake band is mounted on the upper end of the bolt 27 which is displaceably guided in the bracket head 37. The tension of the brake band is determined by the brake spring 31 engaging on the lower end of the bolt 27. Neither in this case is there any change in the braking conditions during the dismantling and fitting of the warp beam, because the collar 29 of the bolt 27, after detaching the brake band 40, holds firmly together the parts which determine the strength of the braking effect.

A tube is preferably used on the whip bar 3, which is pivotally mounted in bearings 41 by means of eccentric end pins 15. However, a differently shaped whip bar, for example, a beam-like whip bar may be employed. The arrangement of a guide rod 42 below the whip bar has the advantage that the warp 7 always runs on to the same point of the circumference of the whip bar, independent upon the varying diameter of the warp beam ball. That is evident from Figs. 2 and 3 where the conditions are shown during the large and/or the small ball diameter.

The embodiments illustrated, show the invention in connection with shoe brakes and band brakes. However, the invention may also be used accordingly with different brake devices, for example chain brakes. In every case of application it is important that the warp beam remains braked with certainty for so long as the torque of the warp tension p acting on the lever arm 16 is smaller than the torque exerted thereon by the spring 12, whilst in the case of the torque exerted by the warp tension p outweighing the torque of the spring 12 the brake is slackened periodically each time in such a manner that the warp beam is able to rotate for a little by the pull of the warp and capable of letting off the warp 7.

In the case of very sensitive cloth in which the tensile pull of the warp must be very small, a slightly pretensioned spring 43 is provided between the brake shoes 18, 19, which spring is able to compensate the weight of the upper brake shoe 19, so that during the periodic slackening of the brake, the upper brake shoe 19 is not left lying on the brake disc 14 exerting a braking action by its own weight.

The new brake is only required on one side of the machine, which is an advantage for the accessibility particularly in limited spacial conditions. For the purpose of slackening the brake by hand an eccentric lever 44 is provided which engages between the two shoes 18, 19.

I claim:

1. In a loom, a warp let-ofi mechanism, comprising, in combination, a turnable warp beam adapted to let off wraps during turning thereof; pivotally mounted whip bar means having a warp supporting surface portion spaced from the pivot axis thereof and adapted to support warps let off by said warp beam to extend normal to an axial plane passing through said surface portion so that the tension of woven warps tends to pivot said whip bar means in let-off direction of said warps; a lever secured to said whip bar means for pivoting about the pivoting axis of the same and extending substantially normal to the direction defined by said warp supporting surface portion and said pivoting axis; warp beam brake means associated with said Warp beam and being movable between a releasing position releasing said warp beam for let off of warps and a holding position; brake spring means urging said warp brake means into said holding position; a double armed lever means having a fixed pivoting point and having a shorter arm and a longer arm, said shorter arm being shorter than the distance between said warp supporting surface portion of said whip bar means from the pivoting axis of said whip bar means and cooperating with the said brake means; adjustable balancing spring means acting on said longer lever arm to turn said lever means into an inoperative position permitting actuation of said brake means by said brake spring means; and link means connecting said lever and said longer lever arm, the arrangement being such that normal warp tension is balanced by said balancing spring means, while increased tension of the warps pivots said whip bar means, said lever, and through said link means said lever means into a position in which said shorter lever arm engages and releases said brake means permitting let off of warps.

2. A warp let-off mechanism, as claimed in claim 1, and including brake release means interconnecting said shorter arm of said lever means with said warp beam brake means.

3. A mechanism as claimed in claim 2 wherein said brake means include two brake shoes, one of said brake shoes being movable and the other brake shoe being fixed; a bolt passing through said brake shoes and having at one end an abutment portion abutting against said mov- 5. able brake shoe and at the other end another abutment portion; and wherein said brake spring means are located between said other abutment portion and said fixed brake shoe, and wherein said shorter arm of said lever means cooperates with said other end of said bolt to compress said brake spring means for releasing said brake means.

4. A mechanism as claimed in claim 3 wherein said abutment portions are detachable nut means, and including a fixed flange on said bolt located between said brake shoes to prevent falling out of said bolt when said movable brake shoe is opened.

5. A mechanism as claimed in claim 1 wherein said brake means includes a brake band; a support secured to one end of said brake band, and formed with a bore; and a bolt secured to the other end of said brake band passing through said bore; and nut means on said bolt spaced from said support, and wherein said brake spring means is located between said support and said nut means, and wherein said short lever arm actson said bolt to compress said brake spring means when said whip bar means turns in said let-off direction.

6. A mechanism as claimed in claim 1 wherein said whip-bar means is a cylindrical member having said pivoting axis eccentrically located.

7. A mechanism as claimed in claim 1 and including an adjustable stop associated with said lever means for limiting turning movement of the same due to the action of said adjusting balancing spring means.

8. A mechanism as claimed in claim 1 and including an adjustable screw mounted on said shorter arm of said lever means and cooperating with said brake means.

References Cited in the file of this patent UNITED STATES PATENTS 617,045 Poyser et a1. Jan. 3, 1899 909,596 Herzberg Jan. 12, 1909 941,201 Keller Nov. 23, 1909 1,487,562 Hawkins Mar. 18, 1924 1,659,236 Bodie Feb. 14, 1928 2,033,558 Van Heek Mar. 10, 1936 2,441,680 Wakefield May 18, 1948 

